Background and aims There has been no comprehensive evaluation of the efficacy of transcutaneous electric nerve stimulation (TENS) for acute low back pain (LBP). The aim of this systematic review was to investigate the efficacy and safety of TENS for acute LBP. Methods We searched MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, CENTRAL, CINAHL and PsycINFO (inception to May 2018) for randomised placebo controlled trials. The primary outcome measure was pain relief in the immediate term (within 2-weeks of administration) assessed using the 100 mm visual analogue scale. A mean difference of at least 10 points on the 100-point pain scale was considered clinically significant. Methodological quality of the eligible studies was assessed using the PEDro scale and overall quality assessment rating was assessed using GRADE. Results Three placebo controlled studies (n = 192) were included. One low quality trial (n = 63) provides low quality evidence that ~30 min treatment with TENS in an emergency-care setting provides clinically worthwhile pain relief for moderate to severe acute LBP in the immediate term compared with sham TENS [Mean Difference (MD) – 28.0 (95% CI – 32.7, -23.3)]. Two other studies which administered a course of TENS over 4-5 weeks, in more usual settings provide inconclusive evidence; MD -2.75 (95% CI -11.63, 6.13). There was limited data on adverse events or long term follow-up. Conclusions The current evidence is insufficient to support or dismiss the use of TENS for acute LBP. Implications There is insufficient evidence to guide the use of TENS for acute LBP. There is low quality evidence of moderate improvements in pain with a short course of TENS (~30 min) during emergency transport of patients to the hospital. Future research should evaluate whether TENS has an opioid sparing role in the management of acute LBP.